1. Field of the Invention
The present invention relates to a digital television (TV), and more particularly to a digital TV that processes an On-Screen Display (OSD) for analog broadcasts and an OSD for digital broadcasts in an integrated manner.
2. Description of the Related Art
Currently provided broadcasts include both analog and digital broadcasts. Thus, current digital TVs have been manufactured so as to be able to receive not only digital broadcast signals but also analog broadcast signals.
FIG. 1 is a block diagram of a conventional digital TV. The configuration of the conventional digital TV is described below with reference to FIG. 1.
The conventional digital TV includes a digital tuner 110, an analog tuner 112, a demultiplexer 120, an MPEG decoder 122, an audio digital-to-analog converter (DAC) 124, a first controller (MICOM 1) 130, a first OSD generator 140, an image processor 150, a video analog-to-digital converter (ADC) 160, an analog amplifier 162, a speaker 164, a second controller (MICOM 2) 170, a display 180, and a key input unit (not shown). The digital tuner 110 receives digital broadcast signals, and the analog tuner 112 receives analog broadcast signals. The demultiplexer 120 divides a digital broadcast signal received through the digital tuner 110 into audio and video signals. The MPEG decoder 122 processes the audio and video signals divided by the demultiplexer 120. The ADC 160 converts an analog video signal of the analog broadcast signal received through the analog tuner 112 into a digital video signal. The analog amplifier 162 amplifies both an analog audio signal of the analog broadcast signal received through the analog tuner 112, and an analog audio signal, which is produced by the DAC 124 through conversion of a digital audio signal output from the MPEG decoder 124. The speaker 164 outputs audio signals amplified by the analog amplifier 162. The key input unit (not shown) receives user commands for selecting and setting various functions of the digital TV. The first OSD generator 140 generates an OSD signal for the digital broadcast signal according to user commands input through the key input unit (not shown), and outputs the generated OSD signal to the image processor 150. The first controller 130 controls the first OSD generator 140 to display an OSD screen on the display 180 and controls the overall operation of the digital TV to perform various functions according to user commands input through the key input unit.
The term “OSD” refers to any type of information such as text, a figure, and a menu, other than broadcast images, displayed on the display 180 to indicate states of the digital TV and allow the user to input commands for setting and changing parameters of various functions of the digital TV. For example, the OSD includes a channel number input field, time information, and menu information, which are overlaid on broadcast images on the display 180.
Since current broadcasting systems provide both analog and digital broadcast signals, the first OSD generator 140 for digital broadcast signals and the second OSD generator 152 for analog broadcast signals are individually provided in the conventional digital TV as shown in FIG. 1.
The second OSD generator 152 is embedded in the image processor 150, and the second controller 170 is separately provided to control the second OSD generator 152.
The image processor 150 includes the scaler 154 that functions to appropriately adjust the resolution of video images or graphics input to the image processor 150. The second controller 170 also controls the scaler 154.
The second controller 170 further controls image quality-related aspects of the picture displayed on the display 180, such as brightness, contrast, sharpness, color temperature, and RGB color.
The digital TV configured as described above operates in the following manner. If the user selects a channel through the key input unit (not shown), the digital tuner 110 or the analog tuner 112 tunes in to the selected channel and receives its broadcast signals.
A digital broadcast signal (ATSC) received through the digital tuner 110 is divided into audio and video signals through the demultiplexer 120 and the MPEG decoder 122. An analog broadcast signal (NTSC) received through the analog tuner 112 is converted into a digital video signal through the video ADC 160, which is then output to the image processor 150.
That is, digital and analog broadcast signals are received through the digital and analog tuners 110 and 112, respectively, and the received digital and analog broadcast signals are separately processed as shown in FIG. 1.
If the user selects an OSD key on the key input unit, for example, on a remote controller or on a key panel provided on the main body of the digital TV, the first or second controller 130 or 170 detects this selection and controls the first or second OSD generator 140 or 152 to display various digital and analog function menus in the form of an OSD on the display 180.
In the conventional digital TV described above, an OSD associated with a digital broadcast and a video image layer are combined into a single digital video signal, which is then transferred to the image processor 150. Even if a digital signal having a very high image quality is transferred to the image processor 150, the image quality of the OSD associated with the digital broadcast is lowered since the scaler 154 and the second OSD generator 152 in the image processor 150 are controlled by the second controller 170 responsible for controlling analog signals.
In order to receive digital and analog broadcast signals, the conventional digital TV includes the digital tuner 110 and the analog tuner 112 and a plurality of controllers (MICOM 1,2) 130 and 170 for controlling the tuners 110 and 112. The controllers 130 and 170 have different responsibilities.
The first controller 130 is responsible for controlling the digital tuner 110, managing digital channels, and controlling other operations of the digital TV, which are associated with the digital tuner 110. The second controller 170 is responsible for controlling the analog tuner 112, managing analog channels, and controlling display image quality or the like.
In the conventional digital TV, in order to draw and display an OSD associated with a digital broadcast, which includes an Electronic Program Guide (EPG), a digital channel related menu, and a digital channel list, on the display 180, the first controller 130 responsible for controlling the digital tuner 110 controls the separate OSD generator 140 to generate an OSD, and combines the generated OSD and a digital broadcast image into a single video signal, and then transfers the single video signal to the image processor 150.
Since an OSD image associated with a digital broadcast is not generated by the OSD generator 152 in the image processor 150 but is instead combined into a single video signal and then transferred to the image processor 150, the image quality of the OSD is lowered.
In addition to the lowered OSD image quality, since OSDs associated with digital and analog broadcasts are generated respectively by the first and second controllers 130 and 170 having different performance and characteristics, it is difficult to manage analog and digital channels in an integrated manner, and also the generated digital and analog broadcast OSDs have different formats. Even if OSDs associated with digital and analog broadcasts are designed to have the same format, they are different in terms of format in actual implementation since the controllers 130 and 170 and the OSD generators 140 and 152 for generating OSDs associated with digital and analog broadcasts have different performance.
Further, the first controller 130 for controlling the digital tuner 110 and the second controller 170 for controlling the analog tuner 112 do not perform data management in an integrated manner, thereby lowering their processing performance.